Random shutdowns and restarts...where to begin?

Question

This is a client's machine.
It is a second generation G5, 17". It passes all TechTool tests. We have the back cover removed to check for overheating. Thus far, we have not been able to duplicate the problem of the shutdowns and restarts...but the machine is essentially idle all day. The processor is not really being used, so it is not an accurate test.
1. Is there are software utility that will put a load on the processor so that we can recreate the issue?
2. Does this have any known heating issues, like the 20" of this series that were recalled?
Thanks in advance for any help.
G5   Mac OS X (10.4.8)  

Answer 1

One not uncommon cause of this problem can actually be the very simple matter of a misaligned power cord collar, Bailey's Dad - see http://docs.info.apple.com/article.html?artnum=86817
This might also help to explain why the behviour hasn't been easy to replicate after the move and with the back taken off. Maybe it is now properly seated!
Putting it under load would be a good idea , though. A power supply issue is not out of the question. The SETI "BOINC" software - http://setiathome.berkeley.edu/ - can be used to create an ongoing artificial load. Playing or rendering videos works pretty well (as Miriam has already suggested) too though. So does running "Classic" applications, using the Classic OS9 emulation.
Printing will provide a short term load on the processor and power supply, too.
THe "Rev B" extended repair program that Miriam has linked to only applies to the 20" model , I'm afraid, not the 17".
Cheers
Rod